5v regulator on positive leg of chipamp PSU

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mandocaster

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Joined 2019
I'm thinking of embedding a raspberry pi in my existing chipamp's enclosure to run RuneAudio.


I want to use a 5v regulator and attach the circuit to the positive output of my chipamp's unregulated power supply.


My question is, with the Pi running at maybe 3A (max), will this extra current being drawn on just the positive rail, cause an imbalance in the +/- power supply, which could cause a DC offset on the output, or have other deleterious effects?


If I have to, I will get a second transformer just for this circuit. I have the room. But it would be cheaper/easier if I could just run it off the existing transformer/rectifier.


Thanks!
 
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benb

Member
Joined 2010
mandocaster said:
Yeah, it was gonna be a switching regulator. Kinda hard to find linear ones with enough amperage while still not needing more heatsink. The unbalanced supplies are what I was worried about. No biggie, I can throw in a 12v transformer just for the pi.
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With a switching regulator it will pull proportionately less current from the rail (minus some inefficiency), but still...

Is the power supply (and thus line voltage) also in the same case? I'd get one of those several-amp-output wall-wart supplies they sell for the Pi and wire the plug-in blades to the chipamp supply primary.
 
M

mandocaster

Member
Joined 2019
Would the pi draw 3A? Not by itself. A Pi 3 is rated at 2A max. I'm not sure how much the DAC hat draws, and I'll have a wifi dongle attached to the USB. So I'm just being conservative. Probably 2A would be the most I'd ever draw, but I like to have a little extra. Besides, then I could add a future 5v device.



I think I've decided I'm going to put a PMC-06V-15W1AA inside the enclosure to power the Pi. Cheap & easy, and looks pretty good quality for a switching supply.
 
JMFahey

JMFahey

Member
Joined 2009
mandocaster said:
Would the pi draw 3A? Not by itself. A Pi 3 is rated at 2A max. I'm not sure how much the DAC hat draws, and I'll have a wifi dongle attached to the USB. So I'm just being conservative. Probably 2A would be the most I'd ever draw,
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You have NOT told us a most important information: WHAT is the rail voltage for your Power Amp? ;)
I ran the two fans in series so I am not dropping lots of watts in the resistors. Madness in my methods !
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Of course that is the sensible way :D

And hanging one from each rail more than duplicates waste.
 
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